Power wrench



April 30, 1968 A. B. CAMPBELL 3,380,323

POWER WRENCH Filed Feb. 15, 1966 5 Sheets-Sheet 1 I I I 74- g LN] 1M i iI I I 0 90 94 J I O O 7? firm/roe.

ANDREW ,8. (32441 5524, (-83 Ms flrmeueg: Himms, 1615a,, floss-e2: 5K

April 30, 1968 A. s. CAMPBELL POWER WRENCH 5 Sheets-Sheet .3

Filed Feb. 15, 1966 INVENTOR. Av qew r51 (EMPBEAL B MS firm/easy:.HlQR/S, 6155, flussszz Mp April 30, 1968 Filed Feb. 15, 1966 A. B.CAMPBELL POWER WRENCH 5 Sheets-Sheet 5 April 1963 A. B. CAMPBELL3,380,323

POWER WRENCH Filed Feb. 15, 1966 5 Sheets-Sheet 4 133 INVENTOR. 66Amman/,5. @MPBELL,

J RP/S Mam flussezz. #1456 12 United States Patent 0 3,380,323 PSWERWRENCH Andrew B. Campbell, San Marino, Califi, assignor toHillman-Kelley, Los Angeles, Calif., a partnership Filed Feb. 15, 1966,Ser. No. 527,720 2 Claims. ((31. 8154) ABSTRACT OF THE DISCLOSURE Apower wrench comprising a housing, an annular rotor rotatable relativeto the housing, a reversible motor for rotating the rotor in eitherdirection, a jaw assembly carried by the rotor and rotatable relativethereto about the rotor axis, a brake for restraining the jaw assemblyto enable the rotor to rotate relative thereto, a double acting camsystem for closing the jaw assembly in response to rotation of the rotorrelative to the jaw assembly in either direction, a first set of stopson the rotor and the jaw assembly for preventing rotation of the rotorrelative to the jaw assembly in one direction to prevent the cam systemfrom closing the jaw assembly, a second set of stops on the rotor andthe jaw assembly for preventing rotation of the rotor relative to thejaw assembly in the other direction to prevent the cam assembly fromclosing the jaw assembly, and a control system for selectivelyinterengaging the stops of the first set and the stops of the secondset. The control system includes a control lever extendingcircumferentially of the rotor and sloping downwardly in the directionof jaw-closing rotor rotation.

Backgrmmd of invention The present invention relates in general to powertongs or wrenches and, more particularly, to a power wrench for makingor breaking threaded joints in pipe or rod strings when running suchstrings into or out of oil wells, for example. Still more particularly,the invention relates to a power wrench capable of lateral engagementwith and disengagement from the pipe or rod string, as by mounting itfor lateral swinging movement into and out of engagement with the pipeor rod string.

The invention contemplates a power wrench of the foregoing type whichincludes a housing, an annular rotor carried by the housing, reversibledrive means for rotating the rotor in either direction, jaw meansmounted on the rotor in such a manner as to permit limited rotation ofthe rotor relative to the jaw means in either direction, double-actingcam means for closing the jaw means in response to limited rotation ofthe rotor relative to the jaw means in either direction from a neutralposition, braking means for restraining the jaw means upon rotation ofthe rotor in either direction to actuate the cam means and thus closethe jaw means, and spring means for biasing the jaw means open inopposition to the action of the cam means so that the jaw means openswhen it is in its neutral position relative to the rotor. Preferably,the housing, the rotor and the jaw means are provided with registerableradial throats permitting radial insertion of a pipe or rod string intothe jaw means into a position to be gripped by the jaw means uponclosing thereof.

With the foregoing construction, the double-acting cam means closes thejaw means in response to rotation of the rotor in either direction, aslong as the braking means restrains the jaw means in order to permit therotor to rotate relative to the jaw means in either direction from therelative neutral positions of the rotor and the jaw means. Consequently,the power wrench can be used for making or breaking a joint in a pipe orrod string merely by reversing the direction of rotation of the rotor.

Patented Apr. 30, 1968 Preferably, the braking means acts on the jawmeans continuously so that the braking means continuously tends toproduce rotation of the rotor relative to the jaw means upon rotation ofthe rotor in either direction. With this construction, the double-actingcam means automatically tends to close the jaw means in response torotation of the rotor in either direction. Consequently, no means foractuating the braking means is required.

However, there are times during the operation of a power wrench of theforegoing nature when it is necessary or desirable to rotate the rotorin one direction or the other without closing the jaw means on a pipe orrod string therein. For example, after making or breaking a joint in apipe or rod string, it is necessary to reverse the direction of rotorrotation to register the radial throats in the rotor and the jaw meanswith the radial throat in the housing so that the power wrench may belaterally disengaged from the pipe or rod string. Initially, suchreversed rotor rotation opens the jaw means to disengage same from thepipe or rod string, and it is necessary to keep the jaw means open asthe reversed rotor rotation continues to register the radial throats inthe jaw means and the rotor with the radial throat in the housing.Otherwise, the previously-completed joint making or breaking operationwould be at least partially reversed, which obviously would beundesirable.

Summary and objects of invention With the foregoing as background, theprimary object of the invention is to provide means for preventingrotation of the rotor relative to the jaw means, in opposition to thecontinuous drag exerted on the jaw means by the braking means, whenclosing of the jaw means is not desired. This permits concurrentrotation of the rotor and the jaw means, with the jaw means open, forthe purpose of aligning the radial throats in the jaw means and therotor with the radial throat in the housing, or for other purposes,which is an important feature of the invention.

More particularly, an important object of the invention is to providemeans for preventing jaw-means-closing rotation of the rotor relative tothe jaw means which includes: firs-t interengageable stop means on therotor and the jaw means for preventing rotation of the rotor relative tothe jaw means in one direction to prevent the cam means from closing thejaw means; second interengageable stop means on the rotor and the jawmeans for preventing rotation of the rotor relative to the jaw means inthe other direction to prevent the cam means from closing the jaw means;and control means for selectively interengaging the first stop means andthe second stop means.

Another important object of the invention is to provide a power wrenchof the foregoing nature wherein: the first stop means includes a firstfixed stop on the jaw means, and includes a first movable stop carriedby the rotor and movable relative to the rotor from an extended positionwherein it is engageable with the first fixed stop to a retractedposition; the second stop means includes a second fixed stop on the jawmeans, and includes a second movable stop carried by the rotor andmovable relative to the rotor from an extended position wherein it isengageable with the second fixed stop to a retracted position; and thecontrol means includes a control lever which has first and second endsrespectively connected to the first and second movable stops, and whichis pivotal ly mounted on the rotor intermediate its ends.

Still another object of the invention is to provide a power wrenchwherein the first and second movable stops are spaced apartcircumferentially of the rotor and the first and second fixed stops arespaced apart circumferentially of the jaw means, and wherein the controllever extends circumferentially of the rotor.

An additional object is to provide a construction of the foregoingnature wherein tilting the control lever relative to the rotor in aparticular circumferential direction will result in closing of the jawmeans when the rotor is rotated relative to the housing in thatdirection. Thus, it is a simple matter for the operator to determinevisually whether the jaw means will close or not upon rotation of therotor in one direction or the other, which is an important feature.

Another object of the invention is to provide first and second fixedstops on the rotor respectively engageable with the first and secondfixed stops on the jaw means, after predetermined rotationaldisplacements of the rotor relative to the jaw means in oppositedirections, to limit the maximum rotational displacement of the rotorrelative to the jaw means which can occur.

Yet another object of the invention is to provide a jaw means whichincludes two jaws and to provide a doubleacting cam means which includesmeans for closing both jaws in response to rotation of the rotorrelative to the jaw means in either direction from a neutral position.

A further object of the invention is to provide a braking means whichincludes a stack of three flat, annular, disc-like braking elementshaving their planes perpendicular to the axis of rotation of the rotor,and which includes spring means for clamping the intermediate brakingelement between the other two, whereby the braking elements cooperate torestrain the jaw means, upon rotation of the rotor in either direction,to actuate the cam means for closing the jaw means. A related object isto provide a braking means of the foregoing character wherein at leastone of the braking elements, preferably the intermediate brakingelement, is carried by the housing, the remainder being carried by thejaw means.

The foregoing objects, advantages, features and results of the presentinvention, together with various other objects, advantages, features andresults of the invention which will be evident to those skilled in thepower wrench art in the light of this disclosure, may be achieved withthe exemplary embodiments of the invention described in detailhereinafter and illustrated in the accompanying drawings.

Description of drawings In the drawings:

FIG. 1 is a perspective view of an apparatus for making or breakingthreaded joints in pipe or rod strings when running such strings into orout of oil wells, for example, which apparatus includes the power wrenchof the invention;

FIG. 2 is a vertical sectional view of the power wrench which is takenas indicated by the arrowed lines 22 of FIGS. 1 and 3;

FIG. 3 is a sectional view taken as indicated by the arrowed line 33 ofFIG. 2, and shows a jaw means of the power wrench of the invention inits open position;

FIG. 4 is a fragmentary sectional view similar to FIG. 3, and shows thejaw means in its closed position;

FIG. 5 is a fragmentary plan view of the portion of the power wrench ofthe invention which is shown in FIG. 4;

FIG. 6 is a fragmentary sectional view taken as indicated by the arrowedline 66 of FIG. 2;

FIG. 7 is a fragmentary sectional view taken as indicated by the arrowedline 77 of FIG. 4;

FIG. 8 is a fragmentary sectional view similar to the bottom part ofFIG. 2, but showing an alternative and presently preferred braking meansof the invention;

FIG. 9 is a sectional view taken as indicated by the arrowed line 9-9 ofFIG. 8; and

FIG. 10 is a fragmentary sectional view taken as indicated by thearrowed line 1010 of FIG. 9 of the drawings.

Description of preferred embodiment of invention Referring initially toFIG. 1 of the drawings, illustrated therein is an apparatus 20 of theinvention for making or breaking threaded joints in pipe or rod strings,such as a threaded joint 22 in a drill string 24. The entire apparatus20 is shown as suspended from a hook 26 at the lower end of a cable, notshown, so that it may be swung laterally into and out of engagement withthe drill string 24.

More particularly, the apparatus 20 includes a vertical post 28 shown ashaving at its upper end an eye 30 engageable with the hook 26. The powertongs or wrench of the invention is designated generally by the numeral32 and is suitably carried by the post 28. As will become apparent, thepower wrench 32 is designed to be engaged with or disengaged from anupper section 34 of the drill string 24 by swinging it to the left orright, as viewed in FIG. I of the drawings. It will be noted that, inthe particular construction illustrated, the power wrench 32 is intendedto engage the upper drill-string section 34 above the threaded joint 22between the upper section 34 and a lower section 36. The threaded joint22 may be of the usual pin and box type, the pin being formed at thelower end of the upper section 34 and the box being formed at the upperend of the lower section 36.

The apparatus 20 is also shown as including a backup tongs or wrench 38engageable with the box at the upper end of the lower drill-stringsection 36 to prevent rotation thereof while making or breaking thejoint 22. The back-up wrench 38, which is more fully described andclaimed by my co-pending application Ser. No. 543,329, filed Apr. 18,1966, is pivotable about a subpost into and out of engagement with thebox at the upper end of the lower drill-string section 36, after thepower wrench 32 has been swung laterally into engagement with the upperdrill-string section 34. The subpost 40 is telescoped upwardly into asocket aligned with the post 28 and is detachably connected thereto by asuitable connector 42. The back-up wrench 38 is supported on the subpost40 by a compression spring 44 seated on a removable pin 46. By removingthe pin 46 and the spring 44, the back-up wrench 38 may he slippeddownwardly off the lower end of the subpost 40 so that it can be turnedover and re-installed on the subpost upside down relative to theposition shown in FIG. I of the drawings. With this construction, theposition of the back-up wrench 38 on the subpost 40 can be reversedreadily when switching from making threaded joints to breaking them, orvice versa. The back-up wrench 38 per se forms no part of the presentinvention, and since it is fully disclosed in my aforementionedco-pending application, it will not be described further herein.

Considering the power wrench 32 of the invention more specifically now,with particular reference to FIGS. 3 to 6 of the drawings, it includes ahousing 50 carried by the post 28 and provided with a radial throat 52for lateral application of the power wrench to and lateral disengagementthereof from the upper drill-string section 34. The outer end of theradial throat 52 is normally closed by two pivoted, spring-biased guards54 which open and close automatically as the power wrench 32 is appliedto and disengaged from the upper drill-string section 34. Guards of thisnature are well known in the power tongs art so that a furtherdescription of the guards 54 is not necessary.

Rotatable in the housing 50 about an axis paralleling that of the post28 is an annular rotor 56 having a radial throat 58 registerable withthe radial throat 52, as shown in FIG. 3, when the power wrench 32 is tobe applied to or disengaged from the drill string 24. As shown in FIGS.2 and 7 of the drawings, the rotor 56 is rotatably mounted in thehousing 50 by means of upper and lower rollers 60 and 62 respectivelyengageable with upper and lower cylindrical surfaces 64 and 66 of therotor, which cylindrical surfaces are, of course, interrupted by theradial throat 58. The weight of the rotor 56 is supported by the upperends of the lower rollers 62, which engage an annular surface 68 of therotor 56 in a plane perpendicular to the axis of rotation of the rotor.The foregoing mounting of the rotor 56 in the housing is generallyconventional so that a detailed description is not required.

The power wrench 32 includes a reversible drive means 70 for rotatingthe rotor 56 relative to the housing 50 in either direction. Referringto FIG. 1, the reversible drive means 70 includes a suitable motor 72mounted on the housing 50. Preferably, the motor 72 is a hydraulic motorhaving connected thereto supply and return lines 74 and 76 which areflexible to permit lateral swinging of the power wrench 32 into and outof engagement with the drill string 24.

The motor 72 may be reversible to drive the rotor 56 in eitherdirection, or a suitable reversing means, not shown, may be interposedbetween the motor and the rotor. In either event, the direction ofrotation of the rotor 56 is controlled by a suitable control lever 78,FIG. 1, carried by the housing 50.

Continuing to consider the reversible drive means 70, it includes asuitable gear train 80, FIG. 3, one end of which is appropriatelyconnected to the motor 72 and the other, or output, end of which isconnected to the rotor 56. More particularly, the output end of the geartrain 80 includes two circumferentially spaced gears 82 meshed with aperipheral gear 84 on the rotor 56. Providing the output end of the geartrain 80 with the two circumferentially spaced gears 82 insures that oneof them will always be in mesh with the peripheral gear 84 on the rotor56, which peripheral gear is interrupted by the radial throat 58 in therotor. The foregoing connections between the rotor 56 and the motor 72are more-orless conventional so that a further description isunnecessary.

The power wrench 32 includes a control system 86 for starting andstopping the motor 72, which control system comprises pivoted controllevers 88 carried by hand grips 90 on the housing 50 on opposite sidesof the radial throat 52 therein. The control system 86 also includesmeans 92, FIGS. 3 and 4, for stopping the rotor 56 with its radialthroat 58 in register with the radial throat 52 in the housing 50. Thecontrol system 86 is more fully described and claimed in the co-pendingapplication of Fred J. Hillman, Ser. No. 543,280, filed Apr. 18, 1966,and assigned to the same assignee as the present application. Thedisclosure of the co-pending application just mentioned is incorporatedherein by reference the same as if it were fully set forth herein.

The power wrench 32 further includes jaw means 94 mounted on the rotor56 in such a manner as to permit limited rotation of the rotor relativeto the jaw means in either direction. More particularly, the jaw means-94 includes a jaw carrier 96 having a radial throat 98 registerablewith the radial throat 58 in the rotor 56 when the jaw carrier is in aneutral position relative to the rotor. The jaw carrier 96 is providedwith cylindrical upper and lower ends 102 and 104 (interrupted by theradial throat 98) which are rotatable relative to the rotor 56 incombined journal and thrust bearing recesses 106 and 108, respectively,in the rotor.

The cylindrical upper and lower ends 102 and 104 of the jaw carrier 96are interconnected by spaced, parallel, chordal guide walls 110 and 112located on opposite sides of the common axis of rotation of the rotor 56and the jaw carrier. The radial throat 98 is formed in the guide wall110.

Disposed between the guide walls 110 and 1-12 are two radially inwardlyand outwardly movable, diametrically-opposed jaw members 114 carryingjaws 116 engageable with the drill string 24. The jaws 116 are shown inengagement with the upper drill-string section 34 in FIGS. 4 and 6 ofthe drawings, and are shown out of engagement with such drill-stringsection in FIG. 3 thereof. Preferably, the jaws 116 comprise removableinserts secured to the jaw members 114 by means of dovetail-like joints.With this construction, other jaws, not shown, for other pipe or rodsizes may be substituted for the jaws 116.

The jaw members 114 are biased apart, i.e., toward their open positions,by a leaf spring 118 disposed between the cylindrical upper and lowerends 102 and 104 of the jaw carrier 96 on the opposite side of the jawcarrier from the radial throat 98 therein. The ends of the leaf spring118 project through windows 120 in the guide wall 112 into grooves 122in the respective jaw members 114. The leaf spring 118 normally assumesthe configuration shown in FIG. 3 of the drawings to bias the jawmembers 114 outwardly into their open positions. When the jaw members114 are forced inwardly into their closed positions in a manner to bedescribed, the leaf spring 118 assumes the configuration shown in FIG. 4of the drawings.

The power wrench 32 further includes double-acting cam means for closingthe jaw means 94 upon rotation of the rotor 56 relative to the jaw meansin either direction away from the relative neutral positions of therotor and the jaw means. This double-acting cam means includes tworoller cam followers 124 respectively carried by the jaw members 114 andrespectively disposed in diametrically-opposite detent recesses 126 inthe rotor 56 when the rotor and the jaw means 94 are in their relativeneutral positions. Upon rotation of the rotor 56 in the counterclockwisedirection relative to the jaw means 94, as shown in FIG. 4 of thedrawings, the cam followers 124 respectively engageradially-inwardly-spiraling cams 128 on the rotor 56 to close the jaws116 on the drill string 24. Conversely, upon clockwise rotation of therotor 56 relative to the jaw means 94 from their relative neutralpositions, the cam followers 124 respectively engageradially-inwardly-spiraling cams 130 on the rotor, which cams also actto close the jaws 116. Thus, upon rotation of the rotor 56 relative tothe jaw means 94 in either direction, the jaws 116 are closed, beingclosed by the interaction of the cam followers 124 and the cams 128 inone direction of relative rotation, and being closed by the interactionof the cam followers and the cams 130 in the other direction of relativerotation.

The power wrench 32 is provided with continuouslyoperating braking means132 for restraining the jaw means 94 upon rotation of the rotor '56- ineither direction so that the cams 128, or the cams 130, close the jaws116.

As suggested in FIGS. 2 and 4, the braking means 132 may comprise abrake band 134 secured to the housing 50 and encircling a brake drum 136on the jaw carrier 96, the brake band 134 being provided with a brakelining 138 engageable with the brake drum. The brake band 134 issuitably secured at its ends to the housing 50 on opposite sides of theradial throat 52 in the housing, as disclosed, for example, in PatentNo. 2,618,468, granted Nov. 18, 1952, to Chester A. Lundeen.

An alternative, and presently preferred, braking means 140 of theinvention is illustrated in FIGS. 8 to 10 of the drawings. The brakingmeans 140 comprises flat, annular, disc-like braking elements 142, 144and 146 having their planes perpendicular to the axis of rotation of therotor 56 and positioned in stacked relation with the braking element 144between the braking elements 142 and 146. The intermediate brakingelement 144 is secured to the housing 50, as by inserting a lug 148thereon into an opening 150 in the housing. It will be understood thatthe intermediate braking element 144 has a gap therein corresponding tothe radial throat 52 in the housing 50. The other braking elements 142and .146, which have gaps therein coinciding with the radial throat 98in the jaw carrier 96, are carried by screws 152 threaded into the lowerend of the jaw carrier. The screws 152 are surrounded by compressionsprings 154 which are seated at their upper ends against the lower endof the jaw carrier 96 and which are seated at their lower ends againstthe braking element 142 to clamp the intermediate braking element 144between the upper and lower braking elements 142 and 146. Thus, thebraking means 140 exerts a continuous restraint on the jaw means 94tending to produce rotation of the rotor 56 relative to the jaw meansupon rotation of the rotor relative to the housing 50.

The description which follows is applicable irrespective of whether thebraking means 132 of FIGS. 2 to 7, or the braking means 140 of FIGS. 8to 10, is used.

As will be apparent, irrespective of the direction of rotation of therotor 56, the braking means 132 or 140 restrains the jaw means 94against rotation to cause the cams 128 or 130 to close the jaws 116 onthe drill string 24. Consequently, the power wrench 32 may be used formaking or breaking the threaded joint 22 merely by reversing thedirection of rotation of the rotor 56. In either case, the jaws 116 gripthe drill string section to which the power wrench 32 is applied with aclamping force proportional to the torque applied to the rotor 56.

As hercinbefore outlined, there are times during the operation of thepower wrench 32 when it is necessary or desirable to rotate the rotor 56in one direction or the other without closing the jaw means 94 on a pipeor rod string therein. For example, after making or breaking thethreaded joint 22, it is necessary to reverse the direction of rotorrotation to first open the jaws 116 and to then register the radialthroats 98 and 58 in the jaw means 94 and the rotor 56 with the radialthroat S2 in. the housing 50 so that the power wrench 32 can bedisengaged from the drill string 24. During this throat-registeringoperation, the jaw means 94 must be kept open to prevent at leastpartial reversal of the previously-completed joint making or breakingoperation.

The invention provides means 160 for preventing rota tion of the rotor56 relative to the jaw means 94, in opposition to the continuous dragexerted on the jaw means by the braking means 132 or 141), when closingof the jaw means is not desired. This permits concurrent rotation of therotor 56 and the jaw means 94, with the jaws 116 open, for the purposeof aligning the radial throats 98 and 58 in the jaw means 94 and rotor56 with the radial throat 52 in the housing 50, or for other purposes.For example, it may simply be desirable under some circumstances torotate the rotor 56 in one direction or the other without rotating itrelative to the jaw means 94 to close the jaw means.

More particularly, the means 160 for preventing jawclosing rotation ofthe rotor 56 relative to the jaw means 94 includes: firstinterengageable stop means 162 on the rotor and the jaw means forpreventing rotation of the rotor relative to the jaw means in theclockwise direction to prevent the cams 130 from closing the jaw means;second interengageable stop means 164 on the rotor and the jaw means forpreventing rotation of the rotor relative to the jaw means in thecounterclockwise direction to prevent the cams 128 from closing the jawmeans; and control means 166 for selectively interengaging the firststop means and the second stop means.

As best shown in FIG. 6 of the drawings, the first and second stop means162 and 164 respectively include first and second fixed stops 168 and176 on the jaw means 94, these fixed stops being formed bycircumferentially spaced ends of an arcuate, circumferentially extendingrib 172 on the jaw carrier 96 and disposed in a circumferential groove174 in the rotor 56. The first and second stop means 162 and 164 alsoinclude first and second movable stops 178 and 180 movable verticallybetween extended and retracted positions and respectively engageablewith the fixed stops 168 and 170, when in their extended positions, inresponse to clockwise and counterclockwise rotation, respectively, ofthe rotor 56 relative to the jaw means 94. As best shown in FIGS. 2 andof the drawings, the

first and second movable stops 1'78 and 180 comprise pins verticallymovable between upper, retracted and lower, extended positions in bores182 and 184 in the rotor 56. The upper ends of the first and secondmovable stops 178 and 180 are pivotally connected to first and secondends 188 and 190 of a circumferential]y-extending control lever 192which constitutes the control means 166 and which is pivotally mountedintermediate its ends, at 194, on the rotor 56.

Considering the operation of the means for preventing jaw-closingrotation of the rotor 56 relative to the jaw means 94, and referringparticularly to FIGS. 2 and 4 of the drawings, it will be assumed thatthe control lever 192 is in the position shown in FIG. 2 and that therotor 56 is being rotated in the counterclockwise direction, asindicated by the arrow 196 in FIG. 4. Under such conditions, the jawmeans 94 is restrained by the braking means 132 or 140 to cause the camfollowers 124 and the cams 128 to cooperate to close the jaws 116 on thedrill-string section 34. It will be noted that with the control lever192 in the position shown in FIG. 2, the second movable stop 180 is inits retracted position so that it cannot engage the second fixed stop toprevent closure of the jaw means 94. It will also be noted that thecontrol lever 192 is tilted relative to the rotor 56 in the direction ofrotor rotation which will produce closing of the jaw means 94. Thus, itis a simple matter for the operator to determine visually that the jawmeans 94 will close when the control lever 192 is tilted downwardly inthe counterclockwise direction and the rotor 56 is rotated in thatdirection.

After the rotor 56 has been rotated in the counterclockwise directionsufliciently to break the threaded joint 22 completely, the direction ofrotor rotation is reversed, without changing the position of the controllever 192. Initially, the rotor 56 rotates relative to the jaw means 94until the rotor and the jaw means are in their relative neutralpositions, with the cam followers 124 in their detent recesses 126.Under such circumstances, the jaw means 94 is fully open. Continuedrotor rotation in the clockwise direction under such circumstancescannot result in re-closing of the jaw means 94 because of the fact thatthe first movable stop 178 engages the first fixed stop 168 to preventjaw-closing rotation of the rotor 56 relative to the jaw means 94. Inother words, the first stop means 162, comprising the first fixed stop168 and the first movable stop 178, precludes jaw-closing rotation ofthe rotor 56 relative to the jaw means 94.

The power wrench 32 has a similar mode of operation when it is desiredto make the joint 22. Under such conditions, the control lever 192 istilted downwardly inthe clockwise direction so that the first movablestop 178 can clear the first fixed stop 168 when the rotor 56 is rotatedin the clockwise direction. Under such conditions, the jaw means 94closes on the drill string section 34. Upon reversed rotation, however,the jaw means 94 opens and does not re-close upon continued reversedrotation.

Thus, in either case, the rotor 56 can rotate relative to the jaw means94 to close the jaw means as long as the direction of rotor rotationcorresponds to the direction of downward inclination of the controllever 192. However, if the direction of rotor rotation is the reverse ofthe direction of downward inclination of the control lever 192, the jawmeans 94 merely opens and then remains open upon continued reversedrotation of the rotor. This permits registering the radial throats 98and 58 in the jaw means 94 and rotor 56 without re-closing of the jawmeans, which is an important feature of the invention.

The power wrench 32 also includes circumferentiallyspaced first andsecond fixed stops 198 and 200 on the rotor 56 and respectivelyengageable with the first and second fixed stops 168 and 170 on the jawmeans 94 to limit the maximum possible relative rotation of the rotorrelative to the jaw means in the clockwise and counterclockwisedirections, respectively. Preferably, the fixed stops 198 and 200 aresimply fixed pins carried by the rotor and respectively engageable withthe ends 168 and 170 of the arcuate, circumferentially extending rib172. Considering the purpose of the fixed stops 198 and 200 withreference to FIG. 4 of the drawings, if the rotor 56 were inadvertentlydriven in the counterclockwise direction without a pipe or rod betweenthe jaws 116, it would be possible for the cam followers 124 to run offthe ends of the cams 128. However, this is prevented by engagement ofthe fixed stop 200 on the rotor 56 with the fixed stop 170 on the jawmeans 94. These fixed stops produce rotation of the jaw means 94 withthe rotor 56 in opposition to the restraining action of the brakingmeans 132 or 140, thereby preventing the cam followers 124 from runningoff the ends of the cams 128. The fixed stops 168 and 198 perform asimilar function during clockwise rotation of the rotor 56 with no pipeor rod between the jaws 116.

Referring to FIG. 2 of the drawings, the relative-rotation-limitingactions of the fixed stops 198 and 200 are supplemented by fixed stops202 and 204 on the rotor 56 and respectively engageable with fixed stops206 and 208 on the jaw means 94. The fixed stops 202 and 204 arepreferably fixed pins aligned with the fixed pins 198 and 200, and thefixed stops 206 and 208 are preferably the ends of an arcuate,circumferentially extending rib 210 coinciding with the rib 172.

Although exemplary embodiments of the invention have been disclosedherein for purposes of illustration, it will be understood that variouschanges, modifications and substitutions may be incorporated in suchembodiments without departing from the spirit of the invention asdefined by the claims which follow.

I claim as my invention:

1. In a power wrench, the combination of:

(a) a housing;

(b) a generally horizontal annular rotor carried by said housing androtatable relative to said housing about a generally vertical axis;

(c) reversible drive means carried by said housing for rotating saidrotor in either direction;

((1) outwardly openable and inwardly closable jaw means carried by saidrotor and rotatable relative to said rotor about said axis;

(e) braking means on said housing and said jaw means for restrainingsaid jaw means upon rotation of said rotor in either direction to enablesaid rotor to rotate relative to said jaw means in either direction;

(f) double-acting cam means on said rotor and said jaw means for closingsaid jaw means in response to rotation of said rotor relative to saidjaw means in either direction from a neutral position;

(g) first interengageable stop means on said rotor and said jaw meansfor preventing rotation of said rotor relative to said jaw means in onedirection to prevent said cam means from closing said jaw means;

(h) second interengageable stop means on said rotor and said jaw meansfor preventing rotation of said rotor relative to said jaw means in theother direction to prevent said cam means from closing said jaw means;

(i) control means for selectively interengaging said first stop meansand said second stop means;

(j) said first stop means including a first fixed stop on said jawmeans, and including a first movable stop carried by said rotor andmovable relative to said rotor from a lower, extended position whereinit is engageable with said first fixed stop to an upper, retractedposition;

(k) said second stop, means including a second fixed stop on said jawmeans, and including a second movable stop carried by said rotor andmovable relative to said rotor from alower, extended position wherein itis engageable with said second fixed stop to an upper, retractedposition;

(1) said first and second movable stops being spaced apartcircumferentially of said rotor and said first and second fixed stopsbeing spaced apart circumferentially of said jaw means;

(m) said control means including a control lever which extendscircumferentially of said rotor, which has first and second endsrespectively connected to said first and second movable stops, and whichis pivotally mounted on said rotor intermediate its ends;

(n) said control lever sloping circumferentially downwardly toward saidfirst movable stop when said first movable stop is in its lower,extended position and said second movable stop is in its upper,retracted position, and said control lever sloping circumferentiallydownwardly toward said second movable stop when said second movable stopis in its lower, extended position and said first movable stop is in itsupper, retracted position; and

(0) whereby the circumferential direction of downward inclination ofsaid control lever corresponds to the direction of rotation of saidrotor required to close said jawrmeans.

2. A power wrench according to claim 1 wherein said control lever is anarcuate member the center of curvature of which lies on the axis ofrotation of said rotor.

References Cited UNITED STATES PATENTS 425,370 4/1890 Coyle l94--122,550,045 4/1951 De Hetre 8157.13 2,618,468 11/1952 Lundeen 81--57.12,766,684 10/1956 Newmaster et a1. 188-83 X 2,846,909 8/1958 Mason8157.1 X 3,103,357 9/1963 Borne 18872 X 3,261,241 7/1966 Cotland 8157.l

FOREIGN PATENTS 334,635 1/1936 Italy.

JAMES L. JONES, JR., Primary Examiner.

